Introduction
Preface To SWARAJ
Punjab, the bread basket of India, the land with 50376 sq. Km is situated in Northern part of India. It is agriculturally Indiaâ„¢s most advanced and most prosperous state. Punjab Tractors limited was promoted by PSIDC as one of its projects in 1970 for the manufacturing of agricultural tractors. Since, this gave independence to country from import of tractors, so brand name SWARAJ, total independence was given.

SWARAJ tractors conceived in 1965 by a team of dedicated engineers and scientists working at Central mechanical Research Institute, Durgapur with a firm belief that Indian Technology could be brought at par with the best in the world. The first model developed was Swaraj-724 developed over a period of 5 years. Independent commercial production started in the year 1974 and after this company grew by leaps and bounds. Today it is one of the leading tractor manufacturing companies.
Origin of the word SWARAJ
In Hindi, the word SWARAJ means freedom from bondage. Since P.T.L. was the only first largest tractor project in India, moreover fully based upon Indian technology. So SWARAJ was appropriately chosen as its brand name. SWARAJ group sells its products under this same brand.
POSITION OF SWARAJ PRODUCTS IN PRODUCTS IN MARKET
With more than 2 lacs of tractors and harvesters combines operating in Indians farms, SWARAJ are now well-established brand name in the country. SWARAJ is now an internationally recognised name in the developing world. The product of SWARAJ is not restricted to Indian market but they have entered in international market. SWARAJ tractors find an important place in developing countries like Ghana, Tanzania, Kenya, Sudan, Uganda, Indonesia and Malaysia, etc. They are also sending their combines to South Korea having first A.C. cabin in India. Long way back, they had also transported the machined rims to Japan, a project millions of dollars.
SWARAJ â€œ A Fascinating Tale Of Growth
A study of PTL history from project stage to its present position of eminence makes a very interesting reading. It is a fascinating story of inspiration, dedication, perseverance and story will to against all adds and prejudices.
PTLâ„¢s Birth
Keeping in mind Punjab agrarian economy it was decided by Punjab government to encourage the growth of industries which compliments Punjabâ„¢s agricultural growth. This task was entrusted to PSIDC that played a major role in bringing Punjab to threshold of industrial revolution. With the dual objective of industrial and agricultural growth, PTL was established on 27 June 1974.
Location
The factory is located at S.A.S. Nagar, the important industrial town of Punjab, 5 km from Chandigarh. The factory was among the first to be set up in this industrial town. The company is managed by board of directors, while the day to day operations are managed by vice-chairman and M.D. of the company.
Export performance of SWARAJ groups
Having established SWARAJ in the national market, the group made a determined start in the 1980â„¢s to get a foothold in the international market. Over the years a large number of SWARAJ tractors and other implements have been exported to many African countries such as Zambia, Kenya, Tanzania and Nigeria and also in the Middle East and South East Asia. Recently it has exported same engines to U.S.A.
INTERNATIONAL AND NATIONAL COLLABORATION OF SAWRAJ GROUP
SAWRAJ groups have entered into technical and financial collaboration with various national and international companies.
SAWRAJ Mazda limited was set with technical and financial collaboration with Mazda Motors Corporation of Japan. After the takeover of SAWRAJ by Mahindra and Mahindra group; Mazda has been dissociated from SAWRAJ group.
SAWRAJ combine division was entered into with Komastu Forklift Company of Japan for manufacturing fork lifters.
SAWRAJ engine limited was set up in technical and financial collaboration with Kirloskar Oil Engines Limited, Pune for manufacturing diesel engines.
RESEARCH AND DEVELOPMENT IN SWARAJ GROUP
Research and development is an integral and sustaining department of any organisation, who wants to sustain its place in the emphasis on research and development in the SWARAJ group is proved by a long list of new products that have been introduced and established in the years ever since the established of SWARAJ group
There is a separate research and development unit of the group located at phase 7 of S.A.S. Nagar (MOHALI). Research work is carried out in this unit and designed work is accomplished. Presently, the research and development is going on with various new products.
Various Companies of SWARAJ Group
Swaraj tractor division
Swaraj engine division
Swaraj combine division
Swaraj automotive division
Swaraj foundry division
SWARAJ TRACTOR DIVISION
It is located in phase-4, industrial area, S.A.S. Nagar (Mohali). The construction work of Punjab tractors limited (PTL) started in March 1972 and the first batch rolled out on 14th November 1973. It started with an annual capacity of 5000 tractors with a capital of Rs. 37 million. In 1974 it went into commercial production with SWARAJ 724, 26.5 bhp as its first model. During its 38 years of production, it has not only expanded its manufacturing capacity to more than 24000 tractors per annum but added more products into its manufacturing range. Its product range includes the following:
Tractors:-
Swaraj 722 super Swaraj 724 FE
Swaraj 733 FE Swaraj 735 FE
Swaraj 744 Swaraj 834 FE Swaraj 855
SWARAJ COMBINES LIMITED
Punjab tractor limited set up the Swaraj Combine Division (SCD) near ChaperCheri village which is located in TEHSIL â€œ Kharar, DISTRICT â€œ Ropar. It was set up with capital outlay of Rs. 2.6 crores to manufacture self propelled harvesters or combines. In 1985, it also brought out diesel fork lifters of 2 tonnes and 2.5 tonnes lifting capacity. Later on the company entered into technical collaboration with Komatsu Fork Lift, which is a Company of Japan for manufacturing both the diesel and electronic fork lifters of capacity up to 10 tonnes. In April 1995, it has also started production of Swaraj 922 tractors
A photo of SWARAJ 8100 HARVESTER COMBINE
SWARAJ AUTOMOTIVE LIMITED
Swaraj automotive limited is situated at Nabha, DISTRICT - Patiala. It was a sick unit before the Swaraj groups over took it. With constant efforts of the new management, now it is again on the path to success. It supplies mudguards and bonnets etc. to the tractor divisions and seats to Maruti.
SWARAJ FOUNDRY DIVISION
Punjab tractors limited set up a captive foundry unit works with an investment of Rs. 1.50 million in the year 1980 for manufacturing the automotive parts. This foundry division is located at village - Majri in the DISTRICT - Ropar at a distance of about 22 Kms. from Chandigarh. Total capacity of this unit is 8000 tonnes of grey cast iron per annum on single shift basis.
SWARAJ ENGINES LIMITED
Swaraj engines limited (SEL), situated at phase 9, industrial area, Mohali was established in the technical and financial collaboration with Kirloskar oil engines for Swaraj tractor division. The governor of Punjab Mr. S.S. RAY laid the foundation stone of the factory on 29th December 1987. It started production from 28th December 1988. In the first year of production only RV-2 engine were produced. In the second year RV-3 engine were introduced. In the third year two more models R-11 and RV-33 were introduced. In 1999 a new RBB engines has also been introduced. During few years of its existence, it has not only increased its product range but also increased its production from 345 in the first year to more than 18000 engines now.
The various engine models produced at SEL are: -
1. RV-2 --------------two cylinders; 24 bhp
2. RV-3 ---------------three cylinders; 39.5 bhp
3. S-15 --------------single cylinder; 25 bhp
4. RB-33 ---------------three cylinders; 55 bhp
5. RB-30 ------------three cylinders; 44 bhp
These engines are sent to the Swaraj tractor division where are fitted on various model tractors. The S-15 engines are manufactured in the Swaraj combine division and are fitted on Swaraj 922 model tractors.
SWARAJ TRACTOR DIVISION
(PUNJAB TRACTOR LIMITED)

PTL HISTORY
1965 Govt. of IndiaËœs research institute(CMERI) at Durgapur initiates design & development of SWARAJ tractor based on indigenous know how.

Swaraj 724 FE
Swaraj 724 FE is a 4 stroke, direct injection diesel run tractor with a capacity of 1728cc and has water cooled cooling system. The tractor has 8 forward and 2 reverse speed gears with high and low selector levels.
Swaraj 724 FE is equipped with self energizing, water sealed disc brakes along with parking brake. The tractor is featured with a single drop arm steering with a centrally located horn switch on the steering wheel. This vehicle is very economical in operations and has a shorter turning radius.

Swaraj 855 is a 4 stroke, direct injection diesel engined tractor ideal for paddy cultivation and suitable for drilling operations with Compressor. This is a 3308cc tractor with 8 forward and 2 reverse speed gears with high and low selector levels.
Swaraj 855 has a self energizing, water sealed disc brakes with parking brake for extra safety and also has an option of an oil immersed disc brake. The tractor is equipped with a single drop arm steering along with an option of a power steering.
Featured Components:
Tractor meter with direction indicators
Fuel gauge
Ammeter
Water temperature gauge
Oil pressure gauge
Lockable battery near starter
Higher capacity diesel tank of 60 liters
VARIOUR DEPARTMENTS IN SWARAJ TRACTOR DIVISION
LIGHT MACHINE SHOP (L.M.S.) AND HEAVY MACHINE SHOP (H.M.S.):
The manufacturing of tractor is performed in various steps. It is manufactured after passing through various processes in various shops. Firstly, various operations on various parts are performed in the L.M.S. and H.M.S. In H.M.S. generally there are four major parts that are given proper machining operations to obtain exact dimension and good surface finish. These include gear box casing, brake hodge, differential housing, trumpet housing and rear cover. Similarly, in L.M.S. the light parts are produced and proper machining is given to them. The various parts include gears, shafts, cage assembly casing etc.
HEAT TREATMENT SHOP
In heat treatment shop, the light parts which are made in L.M.S such as gears, shafts are given the heat treatment to ensure their strength. Firstly the parts after passing through various operations in L.M.S. are taken to the heat treatment shop. Here the part is kept in the furnace for suitable time period up to certain high temperature. Then it is taken to the quenching tank where the hot parts are dipped in the oil. After that the parts are taken to washing tank for washing the parts so that the dirt and oil removed from the parts. Then the treated parts are taken to assembly line.
ASSEMBLY AND PAINT SHOP
In assembly line various parts are being assembled into a single unit termed as tractor. During assembly the various parts are being fitted according to the stage. This would include the assembly of important parts such as rear cover, cover, gear box, differential housing and trumpet housing.
Firstly the various sub-parts of the rear cover are being fitted into the gear box. After that both the rear cover and the gear box are taken to the line where the various things such as brakes, P.T.O. shaft, cage assembly, trumpet housing etc. are fitted to the differential housing. Then this whole assembly is fitted with the engine against the gear box.
After whole assembly is fitted with the engine, this assembly is taken to the Chassis paint area, where it is washed and dry followed by paint on the chassis.
Then the tractor reaches to the final stage where certain electrical and other accessories such as battery cover, steering wheel, radiator etc are fitted. Proper level of engine oil is also filled into the differential and gear box. Greasing of various parts is also performed with grease gun. After that the tractor is taken out of the line after taken it out from the hooks. This stage is termed as dismounting stage. Then the testing of the tractor is performed which include the
checking for vibrations, noise, brakes, oil level and other factors that effects the performance of tractor.
LIGHT MACHINE SHOP
L.M.S. is the largest section of the factory. All transmission components like shafts and gears used tractor are manufactured here. L.M.S comprises of 117 machines, out of which 40 C.N.C. (Computer Numerical Control) machines. Except the bevel gear generator and gear shaver, which have been imported W.M.W. and Churchill (Germany) respectively and all other machines is from H.M.T. Ltd. 160 highly experienced operators and inspectors are working in this shop.
Types of machines: -
S.No. M/C Description Job Operation
Bull Gear Line
1. ECO-5 C bull gear turning
2. Broaching m/c bull gear cutting internal splines
3. Gear hobbing m/c bull gear cutting outer splines
4. Deburring m/c bull gear for removing rough edges
5. Shaving m/c bull gear shaving or finishing

Bull Pinion Shaft Line
6. Centre Facing m/c BP shaft facing, centring
7. Femco turning BP shaft rough, finish turning
8. COOPER BP shaft spline cutting
9. HMT H400 BP shaft gear cutting
10. Shaving m/c BP shaft shaving
Cage assembly
11. VMC-40 Right cage drilling, tapping,
Chamfering, facing
12. Boring m/c Cage assembly boring (both sides)
13. Cylindrical grinding Cage assembly grinding
Machine
14. HMT HMC-320 Cage assembly cross drilling
Other machines
15. Lichberr (HMT) hobbing gear cutting
16. Cooper gear idle cluster cutting
17. Parisuda AHG 80 intermediate grinding
CNC shaft
18. HMT radial drill drilling
19. GCI 300 CNC bevel gear grinding
20. VMC-500 vertical milling, drilling
Milling machine
21. WIDMC drilling m/c drilling
22. PS-180 gear shaper spline cutting
(Not bevel)
HEAVY MACHINE SHOP: -
All heavy castings of tractor are machined in this shop with the help of variety of Special Purpose Machines (SPM). These machines are tailors made by IIMT to suit component requirements. In addition, facilities of this shop include general purpose turning, drilling and milling machines. About 20 special purpose machines and 30 general purpose machines are installed in a covered area of 47000 sq. Ft. At least a cost of 20 million, 2600 tonnes of castings is machined every year on a two shift basis. In addition to the machining of casting for the tractor, some jobs are also performed for Swaraj Mazda Limited.
COMPONENTS MACHINED IN THIS SHOP: -
1. Gear box housing
2. Differential housing
3. Rear cover
4. Trumpet housing
5. Brake hodge
HEAT TREATMENT SHOP:-
Heat treatment shop plays a very important role in every industry. In auto mobile industry all the gears and shafts need to be heat treated to impart desired strength and increase life of the component. This shop in P.T.L. is equipped with several necessary elements. Hardening is done by carburising furnaces, shot blasting furnaces, quenching tanks, induction hardening machines.
Heat treatment is an operation or combination of operations involving heating and cooling of metals and alloys in the solid state to produce certain desired properties. All the heat treatment processes may be considered to consist of three main parts: -
1. The heating of the metal to pre-determined temperature.
2. The soaking of the metal at that temperature until the structure becomes uniform throughout the mass.
3. The cooling of the metal at some pre-determined rate to cause the formation of desirable structure within the metal/alloy for the desired purpose.
Purpose of heating: -
Changes in properties result from the micro-structural changes in material produced by heat treatment operation. However, these serve one or more of the following purpose: -
Improve machinabilitiy.
Relieve internal stresses.
Improve mechanical properties such as ductility, strength, hardness, toughness etc.
Change in grain size.
Increase resistance to heat and corrosion.
Methods of heat treatment: -
Various methods depending upon the nature of job i.e. its material, etc are employed for giving then heat treatment. These methods used are: -
Annealing
Normalizing
Hardening
Quenching
Tempering
Case hardening
(A). Carburizing
(B). Cyaniding
Induction hardening
PAINT SHOP: -
Paint shop is the place where the different sheet metal components are painted. They are made to pass through various chemicals before they are actually painted. The painting method opted is that of spray painting.
Need for painting: -
Long life
Rust resistance
Better look
The various operations performed in paint shop are: -
Surface preparation (pre-treatment cell) â€œ carried out for sheets and rims.
Painting â€œ
Â¢ JOST 1 (dash board, rear frame, front shield, top bonnet)
Â¢ JOST 2 (fenders, side panel)
Â¢ CHASSIS BOOTH (washing, primer, washing zones)
Â¢ FINAL TOUCH UP.
Inspection
Rejection (reprocessing) â€œ for sheets and rims.
Need for surface preparation: -
Removal of:
Â¢ Organic compounds (oil, grease)
Â¢ Inorganic compounds (oxides, peroxides)
Better paint adhesion.
Eliminate chance of reoccurring of dust.
Method of surface preparation: -
Rubbing surface with sand paper
By shot blasting
By buffing
By chemical process.
Chemical processes: -
Here in PTL following chemical processes are done: -
Degreasing
Rinsing (avoid transfer of caustic contents into next acidic process otherwise next acidic process will get disturbed.)
Derusting
Rinsing
Surface activation
Phosphatising (done so as to form a thin layer of coating on part so that no surface remains unpainted)
Rinsing
Passivation (done so as to avoid paint penetration through certain sections of part bodyâ„¢s surface.)
Drying
PAINTING: -
The process of sheet and rim painting includes:-
Full primer + one coat of paint
Flash off (this is the distance given so as to allow the paint to dry)
Baking (120-130 degree centigrade)
Rubbing
Cleaning with tag rag
Final painting
Flash off
Baking
Chassis painting: -
Washing
Drying
Primer painting
Flash off
Final painting
Flash off
Baking
ASSEMBLY SHOP OF SWARAJ TRACTORS: -
Rocker Brake pedal Hanged by
Brakes Link filament conveyor
Cage & Lower link Tractor
Tail pinion filament loaded
Differential
Rear cover Gear box Trumpet
Filament filament filament Engine
coupling
Rear end Gear King pin
cover box filament
Front axle
filament
Trumpet Steering Clutch
filament
ENGINE
ASSEMBLY SHOP
The assembly at Swaraj tractors division deals with the assembly of tractor models 722, 724, 733, 735, 744, 834 & 855. Assembly is the joining of various constituents to form a final product. The assembly process is carried out at main line, which has various sub-assemblies along its length.
Assembly shop can be divided into two main areas: -
Before paint area
After paint area
BEFORE PAINT AREA: -
The area before painting can be further divided into sub-assemblies:
Differential loop
Gear box loop
Rear cover loop
Engine assembly loop
Differential loop: -
1. Differential casting mounted on trolley after washing.
2. Bull pinion shaft left and right fitted.
3. Cage assembly fitted.
It consists of: -
Crown wheel.
Tail pinion assembly.
Roller bearing.
Bevel wheels.
P.T.O. shaft fitted.
Rear axle/trumpet is fitted.
P.T.O. shifter assembly fitted.
Gear box assembly is fitted.
Rear cover assembly is fitted.
Brakes are fitted.
Parking brakes.
Suction pipe.
P.T.O. cover.
Trailer hook is fitted.
Angle bracket is fitted.
Rocket link is fitted.
Footboard is fitted.
Clutch pedal is fitted.
Gear box loop:
1. Gear box housing mounted on trolley.
2. Drive shaft and input shaft assembly.
3. Output shaft assembly.
4. Lay shaft and connecting shaft assembly.
5. Shifter rod assembly.
6. Steering assembly.
Gear box: -
The gear box used in the tractors being made by PTL is of sliding mesh type. This is the simplest type of gear box. The power comes from the engine to the clutch shaft and hence to clutch gear which is always in mesh with a gear on the lay shaft. All the gears on the lay shaft are fixed to it and as such they are all the time rotating when the engine running.
When the clutch is engaged, three direct and one reverse speeds are attained on suitably moving the gear on the main shaft by means of selector mechanism.
Rear cover loop: -
1. Rear cover mounted on trolley.
2. Control valve and response valve assembly.
3. Ram assembly (this consists of cylinder, piston and piston rod).
4. Testing of hydraulic lift.
5. Engine assembly loop:
6. Engine mounted on trolley.
7. Dynamo is fitted.
8. Self-motor is fitted.
9. Oil pump is fitted.
10. Front axle beam and bracket is fitted.
11. Clutch plate is fitted.
After that the chassis is carried to the next level by the lift where the engine and the 3-point assembly of the tractor along with the other components are fixed.
The parts fitted here are: -
Bracket.
Lower link fitted at the left side.
Levelling rod fitted at the right side.
Stabilizer stainer.
Draw bar.
Top link.
Battery frame.
Front frame.
Tie rod attached with the drop arm of the steering system.
Accelerator link.
Delivery pipe.
Engine attachment.
The engine is attached with chassis system in this level of assembly. The engine is also carried to this level with the help of the lift crane, which lifts the engine assembly and delivers it to this level.
Shlug is applied at the corner or we can say at the circumference of the gearbox where engine is attached with studs and bolts. Shlugs works as gaskets or seals and avoid the oil leakage and water mixing in the engine. The engine, which is supplied to this level of assemble where the engine is attached contains the following parts attached on it.
Front axle: -
Extension in the front axle used for the setting of the wheels.
KPSA (King Pin Shaft Axle) with the wheel disc and nuts fitted in there for the fitting of the wheels.
Drop arms
Tie rods
Bucket
Clutch plate
Alternator
Self starter
Fuel pump
These parts are already fitted with the engine when it comes to the engine and chassis assembly. The maker of the engine is KIRLOSKAR or SWARAJ KIRLOSKAR depending upon the model as 3-cylinder, 2-cylinder, or 1-cylinder. The engine was imported from this company from Pune. Swaraj also has its own engine plant where the engines are assembled. After assembling the chassis and engine arrangement, the fitments are checked by the workmen appointed there at this level and if there is some part missing, it is attached here. Then the whole assembly is mounted over the conveyor, which takes that piece to different chambers of washing, drying, primering, baking, painting and again baking.
After painting the conveyor takes the assembled piece to the DISMOUNTING STAGE where the different parts and components are fitted on the tractor and the tractor was completed. After that the testing of the tractor is done. A tractor has to pass through different tests to claim it to be as perfect and if there is some problem coming out in this stage, the tractor is send to the recovery shop, where the problem of the tractor is recovered. After the recovery, the tractor is again tested. Now we shall discuss differential, gear box, rear cover and dismounting stage in detail.
GEAR BOX
The power, which the engine develops, is transmitted to the wheels of the tractor by certain essential parts. The application of engine power to the driving wheels through these parts is called POWER TRANSMISSION. These parts are clutch, gear box, differential and rear axles.
To start a tractor from rest, the inertia of its whole weight must be overcome. Diesel engine does not develop its full power at low speed. It has to run at fairly high speed before it develops maximum power and torque.
Since much power is needed in starting, climbing, uneven land and in pulling varying loads, a provision must be made to permit the engine to run at high speed while the wheels run at lower speed. This is achieved by a system called GEAR BOX.
With the help of gear box we can achieve this and pulling power of the tractor can be increased or decreased by varying the speed tractor. For these tractors gear box used is of the type of SLIDING MESH GEAR type.
Function: -
To convert the power of the engine running at high speed in to low speed at high torque, this is required for starting.
To exchange the forward motion into the reverse motion of the vehicle.
To disconnect the engine from the rear wheels by putting the gear box into neutral position.
LAYOUT OF GEAR BOX ASSEMBLY: -
GEAR BOX SUB-ASSEMBLIES: - are explained below: -
Input shaft: - This shaft transfers the power from the engine to the gear box. One end of the shaft is splined which is connected to the engine and second end is the integral constant mesh pinion which transfers the power to the constant mesh gear splined on the lay shaft.
Lay shaft: - Gears are in the fixed position provided by spacers. Gears on the lay shaft can only rotate but cannot move axially. It consists of one constant mesh gear and three straight teeth gears. Constant mesh gear on lay shaft is in mesh with the constant mesh gear on the input shaft, due to which lay shaft moves with the constant speed. Lay shaft also gives drive to the P.T.O. shaft.
Intermediate shaft: - It is the splined shaft consists of three gears which are axially movable on the shaft. All the gears are provided with the collar, so that forks are fitted in these collars and help the gears to move axially. These gears are meshed with the gears on the lay shaft to have the correct gear pair with required gear ratio. Only one pair is in mesh at one time so to avoid double engaging.
WORKING OF GEAR BOX: -
The constant mesh gear is rigidly fixed to the input shaft or clutch shaft. It remains always connected to the drive gear (also constant mesh gear) of the lay shaft. Three other gears are also rigidly fixed to the lay shaft. They are the second speed gear, first speed gear and reverse speed gear. Two gears are mounted on the splined main shaft or output shaft (also known as intermediate shaft) which can be slided by the shifter fork when the shaft lever is operated. These gears are the second speed gear and first and reverse speed gear. They can be connected to the corresponding gears of the lay shaft and always remains connected to the reverse gear of the lay shaft.
Â¢ Gear in neutral: - When the engine is running and clutch is engaged, the constant mesh gear drives the lay shaft gears. The lay shaft rotates opposite in direction of the clutch shaft. Note that the neutral position, only the constant mesh gear is connected to the constant mesh gear of the lay shaft. Other gears are free, and hence the transmission intermediate shaft is not turning. The vehicle is stationary.
Â¢ First or low speed gear: - By operating the gear shift lever, the larger gear on the intermediate shaft is moved along the shaft to mesh in the first gear of the lay shaft. The intermediate shaft turns in the same direction as the input shaft. Since the smaller lay shaft gear is engaged with the larger intermediate shaft gear, a gear reduction of approximately 3:1 is obtained i.e. the input shaft turns three times for each revolution of input shaft. Further gear reduction in the differential at the rear wheels produces a still higher gear ratio, approximately 12:1, between the engine crankshaft and the wheels.
Â¢ Second speed gear: - By operating the gear shift lever, the larger gear of the intermediate shaft is demeshed from the first gear of the lay shaft and then smaller gear of the input shaft is meshed with the second gear of the lay shaft. The intermediate shaft turns in the same direction as the input shaft. A gear reduction increases this gear ratio to approximately 8:1.
Â¢ Third, top or high speed gear: - By operating the gear shift lever, the second gear of the intermediate shaft and lay shaft are demeshed and then the second and top gear of the input shaft is forced axially against the constant mesh gear of the input shaft. External teeth of the input shaft gear mesh with the input shaft gear mesh with the internal teeth in the second and top gear. The intermediate shaft turns with the input shaft and the gear ratio of 1:1 is obtained. The differential reduction reduces a gear ratio of about 4:1 between the engine crankshaft and the wheels.
Â¢ Reverse gear: - By operating the gear shift lever, the larger gear of the intermediate shaft is meshed with the lever idler gear. The reverse idler gear is always in mesh with the lay shaft reverse gear. Interposing the idler gear between the lay shaft reverse gear and intermediate shaft bigger gear, the intermediate shaft turns in the direction opposite to that of the input shaft. This reverses the rotation of the wheels so that the vehicle backs.
Â¢ High/Low gear: - High/low gear shifter enables to achieve either high torque-low speed or low torque-high speed with the help of planet gear and carrier assembly.
High gear: - Low torque-high torque speed is achieved when hi-lo shifter in high gear position. Coupling intermediate shaft and output shaft with the help of sleeve transmits the power.
Low gear: - High torque-low speed is achieved when hi-lo shifter in low gear position. The power is transmitted to output shaft from intermediate shaft, planet gear and carrier assembly and sleeve. The planet gear and carrier assembly reduces the high speed and subsequently torque is increased.
Lubrication of gear box: -
Proper lubrication of gear bow is extremely important. The transmission gears operate in a bath if lubricant. The fear box should always remain filled with lubricant. It prevents metal to metal
contact which would generate so much heat that the gear teeth would be burned away. It lubricates bearing if the fear box.
PRECAUTIONS IN VARIOUS SUB-ASSEMBLIES: -
Gear box assembly: -
a) Use non-rusty, clean and dry gear box.
b) Check and ensure for no foreign material inside the gear assembly.
c) Check for noise and smooth gear shifting.
Input shaft assembly: -
d) Use clean and rust free components.
e) Ensure due fitment of circlips ball bearing and needle bush.
f) Heat the bearing to (100-110) degree Celsius.
Lay shaft assembly: -
g) Use clean and rust free components.
h) Heat the bearing to (100-110) degree Celsius.
i) Ensure due seating of bearing and circlips.
j) Ensure correct gear painting for specific models.
k) Torque 165 lbs/ft and lock the lock nut.
Idler cluster sub-assembly: -
l) Use clean and rust free components.
m) Ensure due gearing, fitments of needle roller, spacer and thrust washers.
Planet carrier assembly: -
n) Use clean and rust free components.
o) Ensure smooth running, due fitment of planet carrier.
p) Adequate grease and fit the needle rollers.
C.A. assembly: -
q) Use clean and rust free components.
r) Grease the oil seal before use.
s) Ensure due seating of seal and bearing.
t) Apply clean grease between C.A. guide and bush while assembly.
DIFFERENTIAL SYSTEM: -
If the car travels in a straight line, the two rear wheels turn on the road exactly at the same speed. There is in relative movement between two rear wheels. The propeller shaft may be geared rigidly, in the case with the rear axle to rotate the rear wheel together. But when the car takes the turn, the outer wheel travels on the longer radius than the inner wheel. The outer wheel turns faster than the inner wheel, i.e. there is a relative movement between the two rear wheels.
If the two rear wheels are rigidly fixed to a rear axle, the inner wheel will slip which will cause: -
Rapid tyre wear
Steering difficulties
Poor road holding
Therefore, there must be some devices to provide relative movement to the two rear wheels when the car takes a turn and here comes the purpose differential.
The differential is a device is a device that slits the engine torque in two ways, allowing each output to spin at a different speed.
The differential is found on all modern cars and trucks and also in many four-wheel-drive vehicles. These four-wheel-drive vehicles need a differential between each set of drive wheels, one between front wheels and one between rear wheels. The differential has three jobs: -
To aim the engine power at the wheels.
To act as the final gear reduction in the vehicle, slowing the rotational speed of the transmission one final time before it hits the wheels.
To transmit the power to the wheels while allowing them to rotate at different speeds.
Working Of Differential: -
The engine drives the crown wheel mounted on the cage assembly through tail pinion. Four bevel pinions are mounted on the cross, which is fitted in the cage assembly. Cross moves along with the cage assembly and bevel pinions are free to rotate on the cross. Two bevel gears are mounted on the splined bull pinion shaft left and right, which are supported on the taper roller bearings in the differential housing. These taper rolling bearings give rigid support to cage assembly.
CASE-1: -
On straight roads, the cage moves along with the crown wheel carrying the bevel pinions and bevel gears without any relative motion among them. At this time bevel pinions do not revolve around the cross but act as key between bevel gears left and right causing the bull pinion shafts to rotate at the same speed.
CASE-2: -
Now consider that if the tractor is moving and the bull pinion shaft right is being held stationary by applying the brake for a shorter turn in the field, due to this bevel gear right cannot rotate while cage assembly is still rotating in the same direction. As bevel gear right is stationary, bevel pinion will not roll over bevel gear right or we can say it will walk along bevel gear right while revolving around its axis. On the other hand bevel gear left is rotating on its axis due to the speed of cage assembly in the same direction an additional speed has been added due to the relative motion between bevel pinions and bevel gear left.
CASE-3: -
As soon as any of the rear wheels of tractor come across a loose/wet soil where resistance to both the wheels is not equal or when the tractor is on a turn (say right turn), unequal resistance will come across both wheels, causing speed reduction of right wheel and right bull pinion shaft. But the cage assembly will keep on rotating at the same speed and in the same direction. Now bevel pinions will roll over bevel gear right at a slower speed. Hence bull pinion shaft left will rotate at slightly higher speed due to the speed of cage assembly and the additional speed is given to bevel gear left by bevel pinions. This is the working principal of the differential system. On the straight roads the speed of both rear axles remains same and on turns, the inner wheel is subjected to more resistance and hence it moves at a slower speed and outer wheel moves faster.
LAYOUT OF DIFFERENTIAL ASSEMBLY: -
Different manufacturing processes involved in making tractors
1. turning 2. Facing 3.

ABOUT CNC: -
CNC stands for Computer Numerical Control. A CNC is a mini-computer which is used to control the machine tool functions and slide motion from stored information. The instructions are stored in the memory of the mini computer. The instructions are written in the form of program. A CNC system is the heart and brain of a CNC machine which enables the operation of the various machine members such as slides, spindles etc. as per the sequence programmed into it, depending on the machining operations.
The main advantage of a CNC system lies in the fact that the skills of the operator hitherto required in the operation of conventional machine are removed and the part production is made automatic.
A CNC machine tool is different from conventional machine tools in a number of respects. The basic design for conventional machine tool is not suitable for CNC machine. Many design changes are required for CNC machines as compared to conventional machines tools due to addition al requirements of CNC machines such as automatic drive system, high rigidity feed drives, ball screw, automatic tool changer (ATC), chip conveyor, tool magazine.
A CNC machine tool responds directly to the program that is in operation. The accuracy to be achieved depends to a great extent on the various elements of CNC machine. Also the CNC machines have high accuracy and productivity as the machine is operated 24 hours, so need special design for its elements.
ADVANTAGES OF CNC MACHINES: -
1. Availability: - CNC machine can be available for work continuously 24 hours a day, 365 days a year and only need to be switched off for maintenance.
2. User friendly: - CNC machines are user friendly. Less skilled/trained people can operate CNCs unlike manual lathes/milling machines etc. which need skilled engineers.
3. Conversion of units: - If the takes is prepared in the units of inches then the same system of units can be converted into SI units within the computer memory.
4. Updated: - CNC machines can be updated by improving the software used to drive the machines.
5. Diagnostic: - It can diagnose program and can detect the machine malfunctioning even before the part is produced.
6. Easy supervision: - One person can supervise many CNC machines as once these are programmed they can usually be left to work by themselves.
7. Easy training: - Training in the use of CNCs is available through the use Ëœvirtual softwareâ„¢. This is software that allows the operator to practise using the CNC machine on the screen of a computer like a computer game.
8. Similar quality: - CNC machines are programmed with a design which can then be manufactured hundreds or even thousands of items. Each manufactured product will be exactly the same.
9. Reduce inspection: - The time spent on inspection and in waiting for inspection to begin is greatly reduced. Normally it is necessary to inspect the first component only. If there is any difference in the dimensions of the machined component, the program is checked and corrected, if needed.
DISADVANTAGE OF CNC MACHINES: -
1. High initial cost: - CNC machines are more expensive than manually operated machines.
2. Higher maintenance cost: - Persons trained in electronics along with mechanical and electrical are required to service and maintain these complex machines.
3. Skilled CNC personnel: - It is very difficult to find a programmer and operator for a CNC, hence existing personnel must be trained in the programming and operation.

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